How to automatically update tag file in vim?

Question

I use vim C++ tag file for navigation using Ctrl-]. The problem is whenever some file gets modified, the links are no longer valid and I have to re-run ctags and update the tag file. Our code base is huge and it takes quite a while for generating tag file.

Is there any tool which periodically updates the tag file in background? Can I configure VIM to do the same?

I use gvim under Windows.

Answer 1

Further to Blixtor's answer, you'll need to think a little carefully about the design of the script. I'd recommend segregating the design such that the autocommand uses the Windows "start" command or similar to run an external script in the background: thereby preventing Vim from being unresponsive while the tag file is generated.

That script could then generate the tag file using a different file name (i.e. not "tags": ctags -R -o newtags .) and, when ctags is complete, delete tags and rename newtags to tags. This will prevent the tag file from being unavailable in Vim while the generation is done.

Answer 2

I wrote the vim-easytags plug-in to do exactly this. I initialize my tags file once by scanning a whole project (using the command :UpdateTags **/*.[hc] for example) and afterwards the plug-in will automatically update the tags file as I edit and :update my source code files in Vim. While it updates the tags file it will block Vim, but because it only scans the current file it doesn't take long.

Update (2014-07-30): Still working on the vim-easytags plug-in :-). Nowadays it supports an asynchronous mode to avoid blocking Vim. At the time I write this the asynchronous mode is not the default mode yet, but after some more feedback I'll probably switch the default mode.